Shaped expandable material

ABSTRACT

An expandable material is shaped to form a part that can provide functional attributes such as reinforcement to a structure of article of manufacture such as an automotive vehicle.

CLAIM OF PRIORITY

This application claims the benefit of the filing date of U.S.Provisional Application No. 60/729,820 filed Oct. 25, 2005.

FIELD OF THE INVENTION

The present invention relates to a shaped expandable material suitablefor application to an article of manufacture. More particularly, thepresent invention relates to a foamable material that is shaped forapplication to a cavity or other location of a transportation vehiclesuch as an automotive vehicle for providing sealing, baffling,reinforcement, sound dampening, sound attenuation, combinations thereofor the like to the vehicle.

BACKGROUND OF THE INVENTION

For many years industry, and particularly the transportation industryhas been concerned with providing functional attributes sealing,baffling, acoustic attenuation, sound dampening and reinforcement toarticles of manufacture such as automotive vehicles. In turn, industryhas developed a wide variety of materials and parts for providing suchfunctional attributes. In the interest of continuing such innovation,the present invention seeks to provide an improved material and/orimproved part for providing such functional attributes. The materialand/or part can provide sealing, baffling, acoustic attenuation, sounddampening, combinations thereof or the like, but the part and/ormaterial have been found to be particularly adept at providingreinforcement.

SUMMARY OF THE INVENTION

A part is formed of an expandable material and the part is configuredfor providing reinforcement, baffling, sealing or a combination thereofto a structure of an article of manufacture. The part is formed byproviding an expandable material that exhibits a self supportingcharacteristic. The self supporting characteristic is provide throughone or more of partial curing of the expandable material, fast cure timeof the expandable material and/or inclusion of relatively high molecularweight polymeric material, toughened thermoplastic and/or thixotropic orfibrous filler within the expandable material. The part can be shaped bymolding, extrusion or other techniques. Thereafter, the part istypically inserted into a cavity that is at least partially defined by astructure of the article of manufacture. After insertion, the expandablematerial is typically activated to cure, expand and adhere to walls ofthe structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a shaped part formed of expandablematerial in accordance with an aspect of the present invention.

FIG. 2 is a perspective view of another shaped part formed of expandablematerial in accordance with an aspect of the present invention.

FIG. 2B is a cross section of the part of FIG. 2.

FIG. 3 is a perspective view of another shaped part formed of expandablematerial in accordance with an aspect of the present invention.

FIG. 4 is a side view of an exemplary process, machine or both forforming a part in accordance with an aspect of the present invention.

DETAILED DESCRIPTION

The present invention is predicated upon the provision of a shapedexpandable material, a method of forming and/or using the shapedmaterials and articles incorporating the same. The expandable materialcan be employed to form parts for providing functional attributes suchas sealing, baffling, dampening, altervation, reinforcement or acombination thereof to structures of articles of manufacture such asbuildings, appliances, or the like. The parts of expandable material areparticularly adept at providing such functional attributes totransportation vehicles (e.g., boats, trains, automotive vehicles).

Formation of the shaped expandable material typically includes one orany combination of the following:

-   -   1) mixing components to form an expandable material, the        components including one or more polymeric materials, one or        more curing agents and one or more blowing agents;    -   2) shaping the expandable material to form a shaped expandable        part suitable for application to a structure of an article of        manufacture;    -   3) placement of the shaped expandable part adjacent (e.g.,        within a cavity of) a structure of an article of manufacture;        and    -   4) activation of the shaped expandable part such that the part        expands (e.g., foams), adheres to walls of the structure and        cures (e.g., thermosets).

Advantageously, the components and processing of the expandable materialof the present invention can provide a part that is substantiallyentirely homogeneously formed of the expandable material wherein thepart is sufficiently self supporting such that, upon activation of theexpandable material, the part will expand to increase the volumeoccupied by the part without the part significantly losing its shape.Alternatively, however, it is contemplated that the components andprocess may be employed to form a part that does have more significantshape change.

The expandable material may include multiple different components oringredients such as polymeric materials, curing agents, curing agentaccelerators, blowing agents, blowing agent accelerators, fillers,thickeners, surfactants adhesion promoters, combinations thereof or thelike. Typically, the expandable material will be formulated to includeingredients or according to techniques that assist in providing theexpandable material with self supporting characteristics duringactivation of the expandable material. As one example, the expandablematerial will include one or more relatively high molecular weightpolymeric materials for providing self support. As another example, theexpandable material can include fillers (e.g., fibers) that assist inimparting self supporting characteristics to the expandable material. Asstill another example, the expandable material can include a firstcuring agent that at least partially cures the expandable material priorto activation of the expandable material (e.g., during forming,processing and/or shaping of the expandable material) for providing theself supporting characteristics. It is also contemplated that fasterand/or lower temperature curing agents and/or curing agent acceleratorsand/or faster or lower temperature blowing agents and/or blowing agentaccelerators may be employed to minimize foaming and curing times suchthat activation of the expandable material is accomplished while theexpandable material remains self supported. Of course, these materialsor techniques can be employed in combination to form particularlydesirable expandable materials and particularly desirable expandableparts.

Polymeric Materials

It is contemplated within the present invention that various polymersmay be included in the expandable material, e.g., by copolymerization,by blending, or otherwise. For example, without limitation, otherpolymers that might be appropriately incorporated into the expandablematerial include halogenated polymers, polycarbonates, polyketones,urethanes, polyesters, silanes, sulfones, allyls, olefins, styrenes,acrylates, methacrylates, epoxies, silicones, phenolics, rubbers,polyphenylene oxides, terphthalates, acetates (e.g., ethylene vinylacetate (EVA)), methacrylates (e.g., ethylene methyl acrylate polymer(EMA)) or mixtures thereof. Other potential polymeric materials may beor may include include, without limitation, polyethylene, polypropylene,polystyrene, polyolefin, polyacrylate, poly(ethylene oxide),poly(ethyleneimine), polyester, polyurethane, polysiloxane, polyether,polyphosphazine, polyamide, polyimide, polyisobutylene,polyacrylonitrile, poly(vinyl chloride), poly(methyl methacrylate),poly(vinyl acetate), poly(vinylidene chloride), polytetrafluoroethylene,polyisoprene, polyacrylamide, polyacrylic acid, polymethacrylate.

Various isocyanate reactive compounds can be used to form an isocyanatereactive component, which, in turn, can be used to form the activatablematerial. Isocyanate-reactive compounds suitable for the expandablematerial generally include from about 1 to about 8 or moreisocyanate-reactive groups and preferably from about 2 to about 6isocyanate-reactive groups. Suitable compounds include polyacetals,polycarbonates, polyesterethers, polyester carbonates, hydrocarbonspolythioethers, polyamides, polyols (e.g., di- or polyhydric alcohols)such as polyethers, glycols, polyesters and castor oil, polyesteramides,polysiloxanes, polybutadienes, and polyacetones. The isocyanate-reactivecompounds typically contain from about 2 or fewer to about 4 or greaterreactive amino or hydroxyl groups. Isocyanate-reactive compounds can beincluded in the isocyanate-reactive component in an amount of from about5 to about 100% by weight (based on total weight of isocyanate-reactivecomponent), more typically from about 10 to about 90% by weight and evenmore typically from about 40 to about 80% by weight. Preferably,although not required, the above isocyanate-reactive compounds cancreate a blowing effect by liberating a gas (e.g., CO₂) upon reactionwith the isocyanate.

As discussed, the expandable material can include materials having arelatively high molecular weight for assisting in providing self supportcharacteristics to the material. These polymeric materials may beselected from any of the materials discussed herein such as phenoxyresins, urethanes, elastomers, rubbers (e.g., nitrile rubber),isocyanate reactive compounds, polyamides, polyamide alloys, ethylenecopolymers (e.g., EVA or EMA), solid epoxy resins, epoxy/rubber adducts(e.g., carboxylated nitrile rubber/epoxy adducts or CTBN/epoxy adducts),combinations thereof or the like. One preferred material is an epoxybased material and more preferably is a solid bisphenol A epoxy resin.

When included, the percentage of polymeric material in the activatablematerial having a relatively high molecular weight is preferably atleast about 30% by weight but can be less, more preferably at leastabout 50% by weight and even more preferably at least about 65% byweight. As used herein, a relatively high molecular weight is intendedto mean a molecular weight high enough to maintain the polymericmaterial in a solid state at about room temperature (e.g., between about5° C. and about 50° C.). For example, relatively high molecular weightsfor an epoxy-based material (e.g., a bisphenol epoxy based material) aretypically greater than about 1000 or less, more typically greater thanabout 1200 and even more typically greater than about 1400, 2000 or even2750. Relatively high weights for polyamide or polyamide blends aretypically greater than about 10,000 or less, more typically greater thanabout 20,000 and even more typically greater than about 30,000, 40,000or even 50,000.

The polymeric material is typically at least about 25%, more typicallyat least 40% and even more typically at least 60, 70, 80% or more byweight of the expandable material. Of course smaller amounts may be usedwithin the scope of the present invention unless otherwise specificallystated.

Toughened Thermoplastic

The expandable material could also include one or more toughenedthermoplastic materials. Example of thermpoplastics that can betoughened include, without limitation, polyolefin (e.g., polyethylene),polypropylene ethylene methacrylate, ethylene vinyl acetate,thermoplastic epoxy resin, polyester, polyamide, combinations thereof orthe like and such thermoplastic can be toughened with a tougheningmaterial such as tougher thermoplastic, elastomer, thermoplasticelastomer or a combination thereof.

One preferred toughened thermoplastic is a thermoplastic epoxy resin(TPER) reacted and/or toughened with a toughening polymer such as athermoplastic polyolefin or elastomer. Examples of such TPER materialsare poly(hydroxy ethers) or polyetheramines and more particularly,thermoplastic hydroxyl-functionalized polyetheramines (e.g., polyhydroxyamino ethers (PHAE)), which are particularly suitable as thermoplasticsfor the present invention. These polyetheramines are typically formedthrough the reaction of one or more polyfunctional and preferablydifunctional amines with one or more polyfunctional and preferablydifunctional epoxy resins for forming a primarily (i.e., at least 70,80, 90% or more) linear hydroxyl-functionalized polyetheramine resin.Advantageously, the molecular weight of the polyetheramine resin can bemodified by varying the reactant ratios of amine to epoxy. Additionalexamples of suitable PHAEs are disclosed in U.S. Pat. Nos. 5,275,853 and5,464,924, which are incorporated herein by reference for all purposes.

Such original thermoplastic polymers may be toughened with one or moreother toughening polymers (e.g., tougher thermoplastic, elastomer, bothor the like), which can be reacted or grafted onto the originalthermoplastic. Such suitable or original thermoplastic polymers (e.g.,thermoplastic epoxy resins such as PHAE), will include reactive orfunctional groups such as hydroxyl groups, epoxy groups, amine groups,combinations thereof or the like and the toughening polymers suitablefor toughening those original thermoplastics will include (e.g., havebeen modified to include) chemical functional groups such as carboxylicacids, maleic acids or both that are reactive with the functional groupsof the original thermoplastic. Examples of toughening polymers that canbe modified to include such chemical functional groups include, withoutlimitation, tougher thermoplastics such as polyolefin (e.g.,polyethylene), ethylene containing polymer, polyester, polyacrylate,polyacetate, thermoplastic polyolefin (e.g., ethylene methacrylate(EMA), ethylene vinyl acetate (EVA) or both), combinations thereof orthe like and/or elasomer such as polyisoprene, polybutadiene or both.

In one preferred embodiment, a thermoplastic epoxy resin (e.g., PHAE) inaccordance with the previous description of thermoplastic epoxy resinsis toughened with a toughening polymer such as thermoplastic acetate(EVA), thermoplastic acetate (EMA) or both by mixing and/chemicallyreacting the reactive or functional TPER described above with thetoughening polymer where the toughening polymer is functionalized withone or more amine, hydroxyl and/or epoxy reactive groups such as epoxidegroups, carboxylic acid groups, maleic acid groups, anhydride groups,combinations thereof or the like. One example of such a functionalizedtoughening polymer (e.g., a relatively tougher thermoplastic) is aglycidyl methacrylate modified ethylene methacrylate polymer (e.g.,copolymer or terpolymer) sold under the tradename LOTADER AX8950,commercially available from Arkema Chemicals. Another example of such afunctionalized toughening polymer (e.g., a relatively tougherthermoplastic) is a maleic anhydride modified ethylene vinyl acetatesold under the tradename FUSABOND MC 190D or MC 250D, both commerciallyavailable from DuPont. Yet another example of a functionalizedtoughening polymer (e.g., an elastomer, thermoplastic or combinationthereof) is an ethylene butyl acrylate modified with maleic anhydridesold under the tradename LOTADER 3410, also commercially available fromArkema Chemicals.

It shall be understood that such toughening polymer can be reacted withor into (e.g., grafted onto) the original thermoplastic chain of theoriginal thermoplastic according in a variety of ways. Thus, thetoughening polymer can be reacted into the original thermoplastic chainitself, can be pendant relative to the original thermoplastic chain, canbe the end of the original chain or otherwise. Such location of thetoughening polymer will typically depend upon the location of thereactive group (e.g., amine or hydroxyl groups) of the originalthermoplastic (e.g., TPER), the location of the reactive groups (e.g.,epoxide groups, anhydride groups or both) on the tougher thermoplastic(e.g., EVA, EMA or combination thereof) or both. Thus, the toughenedthermoplastic is an original thermoplastic/tougher thermoplastic adductor reaction product (e.g., a TPER/Polyolefin polymer (e.g., copolymer,terpolymer or both)). Examples includes TPER/EVA (e.g., PHAE/EVA)copolymer and TPER/EMA (e.g., PHAE/EMA) copolymer.

The original thermoplastic and the toughening polymer may be mixedand/or reacted according to a variety of protocols. According to apreferred embodiment, the original thermoplastic is melt mixed in anextruder (e.g., a 25 mm twin screw extruder) or batch mixer with thetougher thermoplastic to react the thermoplastics as described. Thedesired temperature for this mixing can vary depending upon thethermoplastics and/or polymers to be mixed and reacted, but aretypically above the T_(g) of the TPER, above the T_(m) of the tougheningpolymer or and about 500° F., more typically between about 300° F. andabout 420° F. and still more typically between about 340° F. and about400° F. Toughening in this manner allows intermixing and reacting of theoriginal thermoplastic and the toughening polymer (e.g., tougherthermoplastic) wherein one or both of the original thermoplastic and thetoughening polymer are solids at room temperature (23° C.) and theirreaction product is also a solid at room temperature. Such solids can beprovided as masses (e.g., pellets, chunks or the like) that can beconvenient for formation, processing or the like. Advantageously, suchtoughened thermoplastic materials can assist in providing selfsupporting characteristics and/or impact strength to the products formedaccording to the present invention.

Examples of suitable toughened thermoplastics (e.g., toughened TPERs)are disclosed in U.S. patent application Ser. No. 60/747,677, titledToughened Polymeric Material and Method of Forming and Using the same,filed May 19, 2006 and U.S. patent application Ser. No. 60/862,113 filedon the same date as the present application and having the same titledas the previous application, both applications being incorporated hereinby reference for all purposes.

Curing Agents and Accelerators

The curing agents and accelerators in the expandable material, as willbe recognized by the skilled artisan, will typically depend upon thepolymeric materials to be cured. Amounts of curing agents and curingagent accelerators can vary widely within the expandable materialdepending upon the type of cellular structure desired, the desiredamount of expansion of the expandable material, the desired rate ofexpansion, the desired structural properties of the expandable materialand the like. Exemplary ranges for the curing agents or curing agentaccelerators present in the expandable material range from about 0.1% byweight to about 7% by weight.

Useful classes of curing agents include materials selected fromaliphatic or aromatic amines or their respective adducts, amidoamines,polyamides, cycloaliphatic amines, (e.g., anhydrides, polycarboxylicpolyesters, isocyanates, phenol-based resins (such as phenol or cresolnovolak resins, copolymers such as those of phenol terpene, polyvinylphenol, or bisphenol-A formaldehyde copolymers, bishydroxyphenyl alkanesor the like), or mixtures thereof. Particular preferred curing agentsinclude modified and unmodified polyamines or polyamides such astriethylenetetramine, diethylenetriamine tetraethylenepentamine,cyanoguanidine, dicyandiamides and the like. An accelerator for thecuring agents (e.g., a modified or unmodified urea such as methylenediphenyl bis urea, an imidazole, 4,4′ methylene bis(phenyl dimethylurea) or a combination thereof) may also be provided for preparing theexpandable material.

Other suitable catalysts or curing agents include tertiary amines andmetal compounds. Suitable tertiary amine catalysts includetriethylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, N,N, N′, N′-tetramethylethylene diamine, pentamethyldiethylene triamine,and higher homologs, 1,4-diazabicyclo[2.2.2]octane,N-methyl-N′-(dimethylaminoethyl)piperazine,bis(dimethylaminoalkyl)piperazines, N, N-dimethylbenzylamine, N,N-dimethylcyclohexylamine, N,N-diethylbenzylamine,bis(N,N-diethylaminoethyl) adipate,N,N,N′,N′-tetramethyl-1,3-butanediamine,N,N-dimethyl-.beta.phenylethylamine,1-methyl imidazole, 1,2-dimethylimidazole, 2-methylimidazole, monocyclicand bicyclic amidines, bis(dialkylamino)alkyl ethers (U.S. Pat. No.3,330,782), and tertiary amines containing amide groups (preferablyformamide groups). The catalysts used may also be the known Mannichbases of secondary amines (such as dimethylamine) and aldehydes(preferably formaldehyde) or ketones (such as acetone) and phenols.

As suggested, faster curing agents and/or accelerators can beparticularly desirable for shortening the time between onset of cure andsubstantially full cure (i.e., at least 90% of possible cure for theparticular activatable material) and curing the expandable materialwhile it maintains its self supporting characteristics. As used herein,onset of cure is used to mean at least 3% but no greater than 10% ofsubstantially full cure that is experienced during activation of theexpandable material. For the present invention, it is generallydesirable for the time between onset of cure and substantially full cureto be less than about 30 minutes, more typically less than about 10minutes and even more typically less than about 5 minutes. It should benoted that more closely correlating the time of softening of thepolymeric materials, the time of curing and the time of bubble formationor blowing can assist in allowing for activation of the expandablematerial without substantial loss of its self supportingcharacteristics. Generally, it is contemplated that experimentation bythe skilled artisan can produce desirable cure times using various ofthe curing agents and/or accelerators discussed above or others. It hasbeen found that for a dicyanamide curing agent or other agents used forcure during activation, other curing agents or accelerators such as amodified polyamine (e.g., cycloaliphatic amine) sold under the tradenameANCAMINE 2441 or 2442 or 2014 AS; an imidazole (e.g.,4-Diamino-6[2′-methylimidazoyl-(1′)ethyl-s-triazine isocyanuric) soldunder the tradename CUREZOL 2MA-OK, both commercially available from AirProducts; an amine adduct sold under the tradename PN-23, an adipichydrazide sold under the tradename ADH both commercially available fromAjinimoto or an adduct of imidazole and isocyanate sold under thetradename LC-65 and commercially available from A & C Catalyst canproduce particularly desirable cure times.

Also, as suggested previously, the expandable material can be formulatedto include a curing agent that at least partially cures the expandablematerial prior to activation of the material. Preferably, the partialcure alone or in combination with other characteristics or ingredientsof the expandable material imparts sufficient self supportingcharacteristics to the expandable material such that, during activation(e.g., curing and/or foaming), the expandable material, which istypically shaped as a part, merely expands volumetrically withoutsignificantly losing it shape.

In one embodiment, the expandable material includes a first curing agentand, optionally, a first curing agent accelerator and a second curingagent and, optionally, a second curing agent accelerator, all of whichare preferably latent. The first curing agent and/or accelerator aretypically designed to partially cure the expandable material duringprocessing (e.g., mixing, shaping or a combination thereof) of theexpandable material for at least assisting in providing the expandablematerial or a part made therefrom with the desirable self supportingproperties. The second curing agent and/or accelerator will thentypically be latent such that they cure the expandable material uponexposure to a condition such as heat, moisture or the like.

As one preferred example of this embodiment, the second curing agentand/or accelerator are latent such that one or both of them cure thepolymeric materials of the expandable material at a second or activationtemperature or temperature range. However, the first curing agent and/oraccelerator are also latent, but either or both of them partially curethe expandable material upon exposure to a first elevated temperaturethat is below the second or activation temperature.

The first temperature and partial cure will typically be experiencedduring material mixing, shaping or both. For example, the firsttemperature and partial cure can be experienced in an extruder that ismixing the ingredient of the expandable material and extruding theexpandable material through a die into a particular shape. As anotherexample, the first temperature and partial cure can be experienced in amolding machine (e.g., injection molding, blow molding compressionmolding) that is shaping and, optionally, mixing the ingredients of theexpandable material. The first curing agent for such and embodimentcould be a curing agent that due to its chemical make-up has aparticular heat at which is cures or it could be a lower temperaturecuring agent that is encapsulated in a material such as a thermoplasticthat fails (e.g., melts or ruptures) at the conditions of processing.

In one embodiment, it is contemplated that a mixer or extruder (e.g., atwin screw extruder) can feed expandable material to an injectionmolding unit. The extruder could feed the injection molding unitdirectly or could feed a reservoir, which in turn feed an injectionmolding unit. In such an embodiment, partial cure or cross-link couldoccur in the extruder, the reservoir, the injection molding unit or acombination thereof.

The second or activation temperature and substantially full cure couldthen be experienced during a temperature experienced during processingof the article of manufacture to which a part of the expandable materialhas been applied. For example, in the automotive industry, e-coat andpaint ovens can provide activation temperatures. Typically, it isdesirable for the expandable material to additionally expand at theactivation temperature as is described more in detail further below.

In this embodiment, partial cure may be effected by a variety oftechniques. For example, the first curing agent and/or accelerator maybe added to the expandable material in sub-stoichiometric amounts suchthat the polymeric material provide substantially more reaction sitesthan are actually reacted by the first curing agent and/or accelerator.Preferred sub-stoichiometric amounts include an amount of first curingagent and/or accelerator that can cause the reaction of no more than60%, no more than 40% or no more than 30%, 25% or even 15% of theavailable reaction sites provided by the polymeric material.Alternatively, partial cure may be effected by providing a first curingagent and/or accelerator that can only react with a percentage of thepolymeric material such as when multiple different polymeric materialsare provided and the first curing agent and/or accelerator are onlyreactive with one or a subset of the polymeric materials. In such anembodiment, the first curing agent and/or accelerator is typicallyreactive with no more than 60%, no more than 40% or no more than 30%,25% or even 15% by weight of the polymeric material. Generally speaking,lower amounts of partial cure typically allow for greater expansion andbetter adhesion while greater amounts often provide greater selfsupport.

In another embodiment, the activatable material may be formed using atwo component system that partially cures upon intermixing of the firstcomponent with the second component. In such an embodiment, a firstcomponent is typically provided with a first curing agent, a firstcuring agent accelerator or both and the second component is providedwith one or more polymeric materials that are cured (e.g., cross-linked)by the curing agent and/or accelerator upon mixing of the first andsecond component. Such mixing will typically take place at a temperaturebelow 140 or 150° C. (e.g., from about 10° C. to about 120° C.).

Like the previous embodiments, the partial cure, alone or in combinationwith other characteristics or ingredients of the expandable material,imparts sufficient self supporting characteristics to the expandablematerial such that, during activation and/or foaming, the expandablematerial, which is typically shape as a part, merely expandsvolumetrically without significantly losing it shape.

Also like the previous embodiments, partial cure may be effected by avariety of techniques. For example, the first curing agent and/oraccelerator may, upon mixing of the first component and secondcomponent, be present within the expandable material insub-stoichiometric amounts such that the polymeric material providesubstantially more reaction sites than are actually reacted by the firstcuring agent and/or accelerator. Preferred sub-stoichiometric amountsincludes having an amount of first curing agent and/or accelerator thatcan cause the reaction of no more than 60%, no more than 40% or no morethan 30%, 25% or even 15% of the available reaction sites provided bythe polymeric material. Alternatively, partial cure may be effected byproviding a first curing agent and/or accelerator that can only reactwith a percentage of the polymeric material such as when multipledifferent polymeric materials are provided and the first curing agentand/or accelerator are only reactive with one or a subset of thepolymeric materials. In such an embodiment, the first curing agentand/or accelerator is typically reactive with no more than 60%, no morethan 40% or no more than 30%, 25% or even 15% by weight of the polymericmaterial.

The other ingredients (i.e., the additional polymeric materials, filler,other additives, the blowing agents and/or accelerators or the like) ofthe expandable material may be part of the first or second components ofthe two component system. Typically, the other additional ingredientswill be split between the components in a manner that allows forreasonably thorough mixing of the first component with the secondcomponent. Generally, this will help the expandable material to besubstantially homogeneous.

The expandable material formed by the two component system can be shapedaccording any of the techniques described herein (e.g., extrusionthrough a die, injection molding or the like). According to onepreferred embodiment, however, the first and second components are bothprovided to and mixed within a die that has one or more cavities thatshape the expandable material as it is mixed and/or partially cured. Assuch, it is contemplated that the two component material may be shapedby high or low pressure casting or reaction injection molding.

Generally, it is contemplated that any of the curing agents and/orcuring agent accelerators discussed herein or others may be used as thefirst and second curing agents for the expandable materials and theagents or accelerators used will typically depend upon the desiredconditions of partial cure and the desired conditions of activation.However, it has been found that, for the first curing agent, amines suchas hindered amines (e.g., sterically hindered), which can be a modifiedpolyamine (e.g., cycloaliphatic amine) sold under the tradename ANCAMINE2337 or 2014 commercially available from Air Products, Inc. areparticularly useful. Curing agents may also be chemically blocked orhindered. Other desirable first curing agents are those that cure thepolymeric materials at temperatures of mixing, formation and/or shaping(e.g., extrusion, molding or the like) of the expandable material. Thus,curing agents that typically cure the polymer materials at temperaturesgreater than 30° C., but possibly less, more typically greater than 50°C. and even more typically greater than 70° C. and/or temperatures lessthan 150° C., more typically less than 120° C. and even more typicallyless than 100° C. It is also contemplated that the first or secondcuring agents can be ambient or elevated temperature curing agents thatare encapsulated in a material such as a thermoplastic that fails (e.g.,melts or ruptures) at the desired temperatures discussed herein or basedupon other conditions such as pressure, to allow for the first or secondcure.

Isocyanate reactive systems (e.g. polyurethane or polyol systems) may bedesigned as two component systems (i.e., a first curing agent thatreacts upon mixing and a second upon exposure to a condition such asheat) or may have a first and second latent curing agent (i.e., a firstand second curing agent that react upon exposure to one or moreconditions such as a first temperature and a second higher temperature).Typically, the latent curing agents are blocked is some manner.

Preferably, although not required, the isocyanates are blocked such thatthe isocyanate component, the activatable material or both aresubstantially devoid of free unreacted (NCO) groups. For example, one ofthe above isocyanates can be reacted to form blocked isocyanates (e.g.,inert adducts) such as urethanes, ureas, alophonate biuret etc., which,at elevated temperatures, can undergo trans-esterification reactionswith the above isocyanate reactive compounds to form polyurethanes,which may be adhesives, foams, combinations thereof or the like. Anexample of one reaction between a blocked isocyanate and a polyol withthe addition of heat is shown in reactive scheme I below:

Typically, the isocyanates are blocked such that they do not react withisocyanate reactive compounds in the expandable material at relativelylower temperatures (e.g., temperatures below about 80° C., moretypically below about 60° C. and even more typically below about 40°C.). However, the blocked isocyanates typically become unblocked atrelatively higher temperatures (e.g., temperatures above about 100° C.,more typically above about 120° C. and even more typically above about160° C.). For unblocking the blocked isocyanates, the expandablematerial should typically be exposed to the elevated temperatures for atleast about 10 minutes or less, more typically at least about 20 minutes(e.g., about 30 minutes) and even more typically at least about 45minutes (e.g., about 60 minutes).

The isocyanates may be blocked using a variety of chemical compoundsdepending upon the desired temperature of unblocking. Pyrazoles such as3,5 dimethyl pyrazole may be employed as the blocking agent when anunblocking temperature between about 100° C. and about 120° C. isdesired. A ketoxime such as Methyl Ethyl Ketoxime may be employed as theblocking agent when an unblocking temperature between about 140° C. andabout 200° C. is desired. An acid ester such as malonic acid ester maybe employed as the blocking agent when an unblocking temperature betweenabout 80° C. and about 100° C. is desired. In one preferred embodiment,a blocking agent such as caprolactam, alkylated phenol or both areemployed to provide an unblocking temperature between about 150° C. andabout 170° C. Isopropyl alcohol may also be employed as a blockingagent. Generally, it is contemplated that the activatable material ofthe present invention may include any of isocyanates discussed hereinand the isocyanates may be blocked with any of the above blocking agentssuitable for blocking the chosen isocyanate.

Exemplary blocked isocyanates include, without limitation, solventlessTDI-prepolymers blocked with one or more alkylated phenols andoptionally including a plasticizer. Examples of such isocyanates havingunblocking temperatures greater than about 160° C. are sold under thetradenames TRIXENE BI 7772 or TRIXENE BI 7779 and are commerciallyavailable from Baxended Chemicals Ltd., Accrington, Lancashire BB5, 2SL,England. Another exemplary blocked isocyanate is a solventless powderdimeric 2,4-Toluene Diisocyanate sold under the tradename DESMODUR TT 44C, which is commercially available from Rhein Chemie Corporation. Yetanother exemplary blocked isocyanate is a solventless 1,6-HexamethyleneDiisocyanate Dimer/Trimer sold under the tradename DESMODUR N-3400,which is commercially available form Bayer AG, 51368 Leverkusen,Germany.

Other exemplary blocked isocyanates include isonate based prepolymersblocked with an oxime (e.g., 2-butanone oxime). Such isocyanates aresold under the tradenames P-1 ISONATE 50 OP MDI/PPG 2000 or P-2 ISONATE50 OP MDI/Tone 0240. Another exemplary blocked isocyanate is isophoronediisocyanate blocked with isopropyl alcohol (IPDI/IPA).

In one particular embodiment, it is contemplated that the expandablematerial may include a single compound that includes a blockedisocyanate and a isocyanate reactive compound. As an example, theexpandable material may include or be substantially exclusively formedof a blocked isocyanate that may also be classified as a polyol. Oneexample of such a blocked isocyanate is a hydroxyl functional uretdion,which preferably does not contain any free NCO groups. Reaction schemeII below illustrated one such isocyanate being turned into apolyurethane by exposure to elevated temperatures which are typicallyhigher than 150° C.

When the activatable material is heat-activated, the heat for activationmay be supplied from a variety of sources such as microwave energy,ionizing radiation, an oven, a thermoelectric device, electrical energy,chemical reaction, combinations thereof or the like. In a preferredembodiment, the expandable material is processed along with an articleof manufacture and the natural processing or assembly steps employed tocreate the article will provide the heat. For example, the expandablematerial may be applied to a structure of an automotive vehicle (e.g.,according to techniques further described below) and may be activated bycoating (e.g., e-coating) or painting operations such as e-coat ovenbake, primer oven bake, paint oven bake, combinations thereof or thelike. Exemplary temperatures encountered in an automobile assembly bodyshop oven, e-coat oven, paint oven or the like may be in the range ofabout 148.89° C. to about 204.44° C. (300° F. to 400° F.).

Whether the activatable material is partially cured or not, the materialcan include polymer/curing agent combinations that are designed to curequickly enough such that the activatable material remains selfsupporting during its cure period. As an example thermoplastic epoxiesor Poly(hydroxy ethers) or polyetheramines cured with isocyanates (e.g.,MDI, TDI or the like). Additional potential polymers for such a fastcure system are disclosed in U.S. Pat. Nos. 5,275,853; 5,164,472;5,464,942; 5,401,814; 5,834,078; 5,962,093; 6,589,621; 6,180,715, all ofwhich are incorporated herein by reference for all purposes. Preferably,the polymers employed have a relatively high molecular weight. Curingtimes for these system are preferably that same from onset of cure tosubstantially full cure as those curing times already discussed herein.

Blowing Agents and Accelerators

One or more blowing agents may be added to the expandable material forproducing inert gasses that form, as desired, an open and/or closedcellular structure within the expandable material. In this manner, itmay be possible to lower the density of articles fabricated from thematerial. In addition, the material expansion helps to improve sealingcapability, substrate wetting ability, adhesion to a substrate, acousticdamping, combinations thereof or the like.

The blowing agent may include one or more nitrogen containing groupssuch as amides, amines and the like. Examples of suitable blowing agentsinclude azodicarbonamide, dinitrosopentamethylenetetramine,4,4_(i)-oxy-bis-(benzenesulphonylhydrazide) (OBSH), trihydrazinotriazineand N, N_(i)-dimethyl-N, N_(i)-dinitrosoterephthalamide.

Some preferred blowing agents are hydrazides or azodicarbonamides soldunder the tradenames CELOGEN® OT and CELOGEN® AZ, commercially availablefrom Crompton, Inc. Preferred physical blowing agent are solventsencapsulated in thermoplastic and sold under the tradename EXPANCEL andcommercially available from Akzo Nobel.

An accelerator for the blowing agents may also be provided in theexpandable material. Various accelerators may be used to increase therate at which the blowing agents form inert gasses. One preferredblowing agent accelerator is a metal salt, or is an oxide, e.g. a metaloxide, such as zinc oxide. Other preferred accelerators include modifiedand unmodified thiazoles or imidazoles, ureas or the like.

Amounts of blowing agents and blowing agent accelerators can vary widelywithin the expandable material depending upon the type of cellularstructure desired, the desired amount of expansion of the expandablematerial, the desired rate of expansion and the like. Exemplary rangesfor the amounts of blowing agents and blowing agent accelerators in theexpandable material range from about 0.1% by weight to about 5 or 10% byweight and are preferably in the expandable material in fractions ofweight percentages.

In one embodiment, the present invention contemplates the omission of ablowing agent. Thus it is possible that the material will not be anexpandable material. Preferably, the formulation of the presentinvention is thermally activated. However, other agents may be employedfor realizing activation by other means, such as moisture, radiation, orotherwise.

Fillers

The expandable material may also include one or more fillers, includingbut not limited to particulated materials (e.g., powder), beads,microspheres, or the like. Preferably the filler includes a relativelylow-density material that is generally non-reactive with the othercomponents present in the expandable material.

Examples of fillers include silica, diatomaceous earth, glass, clay,talc, pigments, colorants, glass beads or bubbles, glass, carbon ceramicfibers, antioxidants, and the like. The clays that may be used asfillers may include clays from the kaolinite, illite, chloritem,smecitite or sepiolite groups, which may be calcined. Examples ofsuitable fillers include, without limitation, talc, vermiculite,pyrophyllite, sauconite, saponite, nontronite, montmorillonite ormixtures thereof. The clays may also include minor amounts of otheringredients such as carbonates, feldspars, micas and quartz. The fillersmay also include ammonium chlorides such as dimethyl ammonium chlorideand dimethyl benzyl ammonium chloride. Titanium dioxide might also beemployed.

In one preferred embodiment, one or more mineral or stone type fillerssuch as calcium carbonate, sodium carbonate or the like may be used asfillers. In another preferred embodiment, silicate minerals such as micamay be used as fillers. It has been found that, in addition toperforming the normal functions of a filler, silicate minerals and micain particular improved the impact resistance of the cured expandablematerial.

When employed, the fillers in the expandable material can range from 10%to 90% by weight of the expandable material. According to someembodiments, the expandable material may include from about 0.001% toabout 30% by weight, and more preferably about 10% to about 20% byweight clays or similar fillers. Powdered (e.g. about 0.01 to about 50,and more preferably about 1 to 25 micron mean particle diameter) mineraltype filler can comprise between about 5% and 70% by weight, morepreferably about 10% to about 20%, and still more preferablyapproximately 13% by weight of the expandable material.

It is contemplated that one of the fillers or other components of thematerial may be thixotropic for assisting in controlling flow of thematerial as well as properties such as tensile, compressive or shearstrength.

Certain fillers, which may or may not be thixotropic, can assist inproviding self supporting characteristics to the expandable material.Preferred examples of such fillers include, without limitation, glass,carbon fibers, graphite, natural fibers, chopped or continuous glass,ceramic, aramid, or carbon fiber or the like.

Other preferred fillers that can provide self support includewollastonite (e.g., a calcium silicate having a needle-like structurewith an aspect ratio of 3:1 to 20:1), aramid pulp or the like. Stillother examples of suitable fillers include, without limitation, talc,vermiculite, pyrophyllite, sauconite, saponite, nontronite,montmorillonite or mixtures thereof. The clays may also include minoramounts of other ingredients such as carbonates, feldspars, micas andquartz. The fillers may also include ammonium chlorides such as dimethylammonium chloride and dimethyl benzyl ammonium chloride. Titaniumdioxide might also be employed. A clay or mineral filler that canprovide desirable rheological characteristic and includes a blend oforganically modified minerals is sold under the tradename GARAMITEcommercially available from Southern Clay Products.

Additives

Other additives, agents or performance modifiers may also be included inthe expandable material as desired, including but not limited to a UVresistant agent, a flame retardant, an impact modifier, a heatstabilizer, a UV photoinitiator, a colorant, a processing aid, alubricant, a reinforcement. chopped or continuous glass, ceramic,aramid, or carbon fiber or the like). As one example, the material caninclude moisture scavenger such as a metal oxide (e.g., calcium oxide).

Examples of suitable formulations for the activatable material areprovided in Table I, II, III below:

Wt. Percent Wt. Percent Ingredients (formula A) (formula B) CTBN/epoxyadduct 14.13 Toughened TPER 9.52 Polyamide alloy 14.13 15.87 Liquidepoxy resin/aramid fiber 2.22 (50:50) Aramide Pulp (Kevlar or 1.41Twaron) Solid Epoxy Resin (500–560 9.04 EEW) Solid Epoxy Resin (575–68514.13 EEW) Solid Epoxy Resin (875–955 8.48 40.63 EEW) (type 4)Epoxy/Elastomer adduct 5.65 Recycled Rubber (fine powder) 2.83 CalciumCarbonate 8.48 21.28 Glass Spheres (hollow, solid or 8.48 2.73 both)Wollastonite 8.49 3.81 Pulverized Dicyandiamide 1.81 1.4 Curing Agentand/or 0.85 0.63 Accelerator (modified aliphatic amine) Latent CuringAgent and/or 0.17 Accelerator (aliphatic amine) Blowing AgentAccelerator 0.62 0.51 (urea) Blowing Agent (OBSH) Blowing Agent 1.131.27 (azodicarbonamide) Pigment 0.17 0.13 100.00 100.00

Above, exemplary formulations of the expandable material are provided.Since they are merely exemplary, it is contemplated that the weightpercents of the various ingredients or properties (e.g., EEWs) may varyby ±50% or more or by ±30% or ±10%. For example, a value of 50 ±10% is arange of 45 to 55. Moreover, ingredients may be added or removed fromthe formulations.

Properties

Generally, it is desirable for the expandable or activatable materialsof the present invention to have certain properties either prior to,during or after activation, however, such properties are not requiredunless otherwise stated. Moreover, values above and below the followingranges are contemplated as being within the present invention unlessotherwise stated. Furthermore, the properties may be determinedaccording to ASTM standards.

Prior to full cure, the activatable or expandable material typically hasa density greater than 0.2 g/cc, more typically greater than 0.6 g/ccand even more typically greater than 0.9 g/cc and also typically lessthan 4.0 g/cc more typically less than 2.0 g/cc and even possibly lessthan 1.3 g/cc. Prior to full cure, the activatable or expandablematerial typically has a viscosity at 100° C. and 200 1/sec. greaterthan 1000 Pa*sec, more typically greater than 1900 Pa*sec and even moretypically greater than 2800 Pa*sec and also typically less than 5000Pa*sec more typically less than 3900 Pa*sec and even more typically lessthan 3000 Pa*sec. Prior to full cure, the activatable or expandablematerial typically has a viscosity at 100° C. and 400 1/sec. greaterthan 800 Pa*sec, more typically greater than 1500 Pa*sec and even moretypically greater than 2000 Pa*sec and also typically less than 3500Pa*sec more typically less than 2800 Pa*sec and even more typically lessthan 2200 Pa*sec. Prior to full cure, the activatable or expandablematerial typically has a viscosity at 100° C. and 600 1/sec. greaterthan 500 Pa*sec, more typically greater than 1100 Pa*sec and even moretypically greater than 1600 Pa*sec and also typically less than 3200Pa*sec more typically less than 2400 Pa*sec and even more typically lessthan 1800 Pa*sec. Prior to full cure, the activatable or expandablematerial typically has a viscosity at 120° C. and 200 1/sec. greaterthan 100 Pa*sec, more typically greater than 500 Pa*sec and even moretypically greater than 850 Pa*sec and also typically less than 2000Pa*sec more typically less than 1400 Pa*sec and even more typically lessthan 1000 Pa*sec. Prior to full cure, the activatable or expandablematerial typically has a viscosity at 120° C. and 400 1/sec. greaterthan 70 Pa*sec, more typically greater than 400 Pa*sec and even moretypically greater than 650 Pa*sec and also typically less than 1600Pa*sec more typically less than 1000 Pa*sec and even more typically lessthan 760 Pa*sec. Prior to full cure, the activatable or expandablematerial typically has a viscosity at 120° C. and 600 1/sec. greaterthan 50 Pa*sec, more typically greater than 300 Pa*sec and even moretypically greater than 500 Pa*sec and also typically less than 1300Pa*sec more typically less than 900 Pa*sec and even more typically lessthan 700 Pa*sec.

After full cure, the activated material typically has a density greaterthan 0.08g/cc, more typically greater than 0.20 g/cc and even moretypically greater than 0.40 g/cc and also typically less than 2.0 g/ccmore typically less than 1.0 g/cc and even more typically less than 0.6g/cc. The expandable material typically expands to a volume that istypically at least 101%, more typically at least 130%, still moretypically 190% and also typically less than 1000%, more typically lessthan 500% and even more typically less than 325% of its originalunexpanded volume. After full cure, the material preferably exhibits alap shear greater than 50 psi, more typically greater than 150 psi andeven more typically greater than 300 psi and also typically less than3000 psi more typically less than 1400 psi and even more typically lessthan 800 psi. After full cure, the material typically exhibits a modulusof greater than 50 MPa, more typically greater than 120 MPa and evenmore typically greater than 200 MPa and also typically less than 3000MPa more typically less than 1300 MPa and even more typically less than800 MPa. Moreover, after full cure, the material typically exhibits apeak stress greater than 0.2 MPa, more typically greater than 1.0 MPaand even more typically greater than 2 MPa and also typically less than200 MPa more typically less than 70 MPa and even more typically lessthan 20 MPa. After full cure, the material also typically exhibitselongation greater than 0.01%, more typically greater than 0.4% and evenmore typically greater than 1% and also typically less than 70% moretypically less than 20% and even more typically less than 8%.

The expandable material, at about room temperature (23° C.), can besubstantially tack-free and/or dry to the touch according to theformulations presented herein. It can also have various degrees of tackas well, however, the substantially tack-free material can beadvantageous for ease of handling.

Mixing and Shaping

As suggested, various types of mixing and shaping techniques may beemployed for forming and shaping the expandable materials. Examplesinclude extrusion, batch mixing, molding (e.g., compression molding,injection molding, blowmolding) or the like. According to oneembodiment, the ingredients of the expandable material are providedseparately, together or as subsets of materials to an extruder and mixedwithin the extruder. In such an embodiment, the expandable material maypartially cure in the extruder due to material mixing and/or due to theheat of mixing. Then, the material may be shaped by an extruder die ororifice and may be further cut to a desired shape. Alternatively, theexpandable material may be mixed and extruded and cut into pellets suchthat the expandable material can be fed to an injection molding machineand further shaped and preferably partially cured. Of course, theexpandable material may be provided to a molding machine in other waysas well (e.g. as ingredients liquid or the like.)

It is also contemplated that the expandable material may be formed orshaped to include one or more fasteners that are integrally formed ofthe expandable material or one or more fasteners can be attached to theexpandable material before or after it has been shaped as a part.Advantageously such fasteners can assist in locating the shapedexpandable parts relative to articles of manufacture.

Generally, parts formed according to the present invention are typicallysubstantially entirely formed of expandable material and can be appliedto structures of articles of manufacture without supports such as moldedcarriers, although not required unless otherwise stated. Typically, theparts of the present invention are at least 50%, more typically at least70% and even more typically at least 80, 90 or even at least 95 or 99.5%by weight expandable material upon application of the part to astructure of an article of manufacture.

Referring to FIG. 1, there is illustrated a part 10 formed of anexpandable material in accordance with an aspect of the presentinvention. As can be seen, the part 10 is being applied to a structure12 (e.g., a pillar, frame member, body member or the like) of an articleof manufacture (e.g., a transportation or automotive vehicle). Theexpandable part 10 is illustrated as being substantially continuouslysolid and homogeneous from a first end 20 to a second end 22 along alength of the part 10. The part 10 is also shown to have one or moresloping walls 30 extending partially or substantially fully along thelength of the part 20. The part 10 is generally conical orfrusto-conical, but could be shaped in a variety of differentconfigurations such as cylindrical, cube, pyramidal, non-geometric orthe like. Typically, although not required, the part 10 has a shape thatsubstantially corresponds to a cavity 34 of the structure 12 into whichthe part 10 is to be inserted.

Assembly of the expandable part 10 to the structure 12 generallyinvolves placement of the part 10 adjacent the structure, but morepreferably includes insertion of the part within the cavity 34 of thestructure 12. As shown, the part 10 includes at least one (e.g., one,two, three or more) fasteners 38, which can assist in at leasttemporarily attaching the part 10 to the structure 12. Such fasteners 38may be integrally formed with the rest of the part 10 of expandablematerial. For example, a die of a molding machine may form the fasteners38. Alternatively, the fasteners 38 may be formed of a differentmaterial such as a metal or thermoplastic and may be connected to theexpandable material of the part 10 using a variety of techniques. As oneexample, the expandable material may be shaped (e.g., insert molded)about a portion of the fasteners 38 such that the fasteners 38 attach tothe expandable material of the part 10. Upon assembly of the part 10 tothe structure 12, the fasteners 38 can be interferingly located inopenings (e.g., cavities, through-holes or the like) of the structure 12or article of manufacture such that the expandable part 10 is located ina predetermined location relative to the structure 12 (e.g., within thecavity 34).

After assembly of the expandable part 10 to the structure 12, the part10 is typically activated to expand (e.g., foam) and cure (e.g.,thermoset). Activation is typically caused by exposure to a conditionsuch as pressure, moisture, radiation or the like. Preferably, theexpandable part 10 activates upon exposure to heat and more particularlyupon exposure to temperatures frequently experienced in an e-coat orpaint oven for automotive vehicles. A part 10 according to the presentinvention may volumetrically expand a variety of different degreesdepending upon the purpose and formulation of the part and/or materialof the part. For reinforcement purposes, it is typically preferable forthe expandable material of the part to expand to a volume that is atleast 102%, more typically 115% and even more typically 140% relative toits original unexpanded volume and it is also typically preferable forthe expandable material of the part to expand to a volume that is lessthan 1000%, more typically less than 500% and even more typically lessthan 300% relative to its original unexpanded volume.

Upon activation, the part 10 typically expands to contact, whet andadhere to walls of the structure 12 and typically walls that define thecavity 34 of the structure 12. In the embodiment of FIG. 1, the partwill typically substantially entirely fill cross-sections of the cavity34 along a length of the cavity 34, although not required. The part 10,after activation, can provide sealing, baffling, dampening, or otherproperties to the structure 12. Preferably, the part providessubstantial reinforcement to the structure 12.

Referring to FIG. 2, there is illustrated another part 50 formed of anexpandable material in accordance with an aspect of the presentinvention. As can be seen, the part 50 is being applied to a structure52 (e.g., a pillar, frame member, body member or the like) of an articleof manufacture (e.g., a transportation or automotive vehicle).

The expandable part 50 is illustrated as being generally skeletal orskeletal along its length. For defining the term skeletal as used hereinonly, the term intersection area refers to an area of a cross-sectionalplane that intersects with expandable material and the term interstitialarea refers to the area of the cross-sectional plane that does notintersect with the expandable material, but is located between portionsof the intersection area. As an example, a cross-sectional plane isillustrated in FIG. 2B and shows intersection areas 56 and interstitialareas 58. Thus, a shaped part is skeletal in nature if, for at least 70%of all cross-sections through the part or perpendicular to an axisextending along a length of the part, the intersection area is less than300%, less than 150%, less than 110% or less than 75, 50 or even 35% ofthe interstitial area for the cross-sections.

Of course, a skeletal part can expand to reduce the amount ofinterstitial area while still being consider to substantially retain itsoriginal non-expanded shape. After expansion, the intersection area istypically less than 500%, less than 350%, less than 210% or less than175, 80 or even 55% of the interstitial area for the cross-sections Itis also contemplated that a skeletal part can expand to substantiallyfill a section of a structure and leave very little or no interstitialarea.

The part 50 is also shown to have one or more sloping walls 70 extendingpartially or substantially fully along the length of the part 50. Thepart 50 could be shaped in a variety of different configurations such ascylindrical, cube, pyramidal, non-geometric or the like. Typically,although not required, the part 50 has a shape that substantiallycorresponds to a cavity 74 of the structure 52 into which the part 10 isto be inserted.

Assembly of the expandable part 50 to the structure 52 generallyinvolves placement of the part 50 adjacent the structure, but morepreferably includes insertion of the part within the cavity 74 of thestructure 52. The part 50 can includes at least one (e.g., one, two,three or more) fastener, which can assist in at least temporarilyattaching the part 50 to the structure 52 such as those previouslydescribed for locating the part in a predetermined location relative tothe structure 52 (e.g., within the cavity 74).

After assembly of the expandable part 50 to the structure 52, the part50 is typically activated to expand (e.g., foam) and cure (e.g.,thermoset). Activation is typically caused by exposure to a conditionsuch as pressure, moisture, radiation or the like. Preferably, theexpandable part 50 activates upon exposure to heat and more particularlyupon exposure to temperatures frequently experienced in an e-coat orpaint oven for automotive vehicles. A part 50 according to the presentinvention may volumetrically expand a variety of different degreesdepending upon the purpose and formulation of the part and/or materialof the part. For reinforcement purposes, it is typically preferable forthe expandable material of the part to expand to a volume that is atleast 102%, more typically 115% and even more typically 140% relative toits original unexpanded volume and it is also typically preferable forthe expandable material of the part to expand to a volume that is lessthan 1000%, more typically less than 500% and even more typically lessthan 300% relative to its original unexpanded volume.

Upon activation, the part 50 typically expands to contact, whet andadhere to walls of the structure 52 and typically walls that define thecavity 34 of the structure 12. In the embodiment of FIG. 1, the partwill typically substantially entirely fill cross-sections of the cavity74 along a length of the cavity 74, although not required. The part 50,after activation, can provide sealing, baffling, dampening, or otherproperties to the structure 52. Preferably, the part providessubstantial reinforcement to the structure 52.

While it is generally typically desirable for the material to adhere tosurrounding walls of a structure upon activation. It may also bepossible in certain application for the material to expand without anysubstantial adhesion and to substantially interference or friction fitwithin a structure upon expansion.

The shapes of the parts can vary widely depending upon the intendedlocation and use of the part. For example, the shaped parts can have acentral portion with extensions or ribs extending outward from thecentral portion. As another example, the parts can be formed with anouter peripheral portion (e.g., a tube or channel shaped portion) thatdefines an internal opening (e.g., a tunnel or channel) and ribs orcross-members may extend fully or partially across and/or through theinternal opening.

According to one preferred embodiment, one or more parts are formed byextruding the expandable material through an extrusion die to attain oneor more desired cross-sectional shapes for the expandable material andthen the extrudate or expandable material is cut when it reach a desiredlength. An example of such a part 100 is illustrated in FIG. 3. Asshown, the part 100 has been extruded through a die to have an outerperipheral portion 102 that is shown as a tubular shape with rectangularor square cross-sections perpendicular to a length (L) of the part 100.Of course, this outer peripheral portion 102 could be channel shaped orotherwise shaped and can have other cross-sectional shapes such ascircular, oval or the like which may be symmetrical or non-symmetrical.As shown, the outer peripheral portion 102 is substantially entirelycontinuous although it could be non-continuous and/or could includeopenings.

The outer peripheral portion 102 typically defines an internal opening108 such as a cavity, a through-hole or the like. As shown, the internalopening 108 is a tunnel extending along the length (L) of the part 100.The internal opening 108 is shown as being substantially entirelyenclosed except at the ends of the part 100, however, openings (e.g.,through-holes or slits) could extend through the peripheral portion 102.The part 100 also includes ribs 110, 112 extending into and/or throughthe internal opening 108. The ribs can extend into the opening and stopor as shown, the ribs 110, 112 can intersect. The ribs can also dividethe internal opening 108 into multiples sub-openings (e.g., cavities,channels or tunnels). In the embodiment illustrated, the internalopening 108 is divided into four tunnels 118 by two intersecting ribs110, 112.

Referring to FIG. 4, it is also contemplated that parts 150 may beformed to include relatively long fibers, which can be carbon fibers,natural fibers, aramid fibers, glass fibers, combinations thereof or thelike according to a pushtrusion process 152. As shown, pellets 158 ofthe expandable material are introduced to a feeder/mixer 164 (e.g., anextruder-like device with a rotating screw) and fibers 154 areintroduced into the expandable material after the expandable materialleaves the feeder/mixer 164. Thereafter, the expandable material withthe fibers is introduced to a molding machine 166 to form parts 150 asshown. Such a pushtrusion process and or device are commerciallyavailable from Plasticomp, Winona, Minn. Advantageously, parts havingaverage fiber length of at least 0.3, more typically at least 0.8 cm,even more typically at least 1.4 cm and even possibly at least 1.8 oreven 2.5 cm can be formed.

Unless stated otherwise, dimensions and geometries of the variousstructures depicted herein are not intended to be restrictive of theinvention, and other dimensions or geometries are possible. Pluralstructural components can be provided by a single integrated structure.Alternatively, a single integrated structure might be divided intoseparate plural components. In addition, while a feature of the presentinvention may have been described in the context of only one of theillustrated embodiments, such feature may be combined with one or moreother features of other embodiments, for any given application. It willalso be appreciated from the above that the fabrication of the uniquestructures herein and the operation thereof also constitute methods inaccordance with the present invention.

The preferred embodiment of the present invention has been disclosed. Aperson of ordinary skill in the art would realize however, that certainmodifications would come within the teachings of this invention.Therefore, the following claims should be studied to determine the truescope and content of the invention.

What is claimed is:
 1. A method of reinforcing a structure of an articleof manufacture, the method comprising: providing an initially solidpellet of expandable material including a first curing agent and havinga self supporting characteristic during expansion thereof that is due tothe presence of the first curing agent causing partial curing of theexpandable material during processing of the pellet, and the inclusionof the following in the expandable material: i) an acrylonitrilebutadiene styrene copolymer material; and ii) a thixotropic or fibrousfiller; injection molding the expandable material into a part; insertingthe part into a cavity that is at least partially defined by a structureof the article of manufacture; and activating the expandable material tocure due to the presence of a second coring agent, so that theexpandable material expands to a volume that is less than 500% relativeto its original unexpanded volume and adheres to walls of the structureand provide structural reinforcement to the structure.
 2. A method as inclaim 1 wherein the expandable material is substantially tack-free tothe touch.
 3. A method as in claim 1 wherein the part, upon activation,forms a foam that exhibits a compressive strength greater than about 5Mpa.
 4. A method as in claim 1 wherein the part is skeletal.
 5. A methodas in claim 1 wherein the article of manufacture is an automotivevehicle.
 6. A method as in claim 1 wherein the parts are substantiallywithout supports and molded camera upon insertion into the cavity.
 7. Amethod as in claim 1 wherein the expandable material is at least 90% byweight of the part upon insertion of the part into the cavity.
 8. Amethod as in claim 1 wherein the part shaped of expandable material is atubular structure with internal ribs, both the tubular structure and theribs being formed of e expandable material and substantially maintainingits shape during expansion.
 9. The method of claim 1, wherein theexpandable material is not in liquid form prior to partial curing.
 10. Amethod of reinforcing a structure of an automotive vehicle, the methodcomprising: providing an initially solid pellet of expandable materialincluding a first curing agent and having a self supportingcharacteristic during expansion thereof that is due to the presence ofthe first curing agent causing partial curing of the expandable materialduring processing of the pellet, and the inclusion of the following inthe expandable material: i) an acrylonitrile butadiene styrenecopolymer, ii) an elastomer and iii) a fibrous filler; injection moldingthe expandable material into a part; inserting the part into a cavitythat is at least partially defined by a structure of the automotivevehicle; and activating the expandable material to cure due to thepresence of a second curing agent, so that the expandable materialexpands to a volume that is less than 500% relative to its originalunexpanded volume and adheres to walls of the structure and providestructural reinforcement to the structure wherein the part substantiallymaintains it's shape during expansion.
 11. A method as in claim 10wherein the expandable material is substantially tack-free to the touch.12. A method as in claim 11 wherein the part, upon activation, forms afoam that exhibits a compressive strength greater than about 5 Mpa. 13.A method as in claim 12, wherein the part is skeletal and substantiallymaintains its skeletal shape during expansion.
 14. A method as in claim12 wherein the parts are substantially without supports and moldedcarriers upon insertion into the cavity.
 15. A method as in claim 10wherein the expandable material is at 90% by weight of the part uponinsertion of the part into the cavity.
 16. A method as in claim 10wherein the part shaped of expandable material is a tubular structurewith internal ribs, both the tubular structure and the ribs being formedof the expandable material.
 17. A method of reinforcing a structure ofan automotive vehicle, the method comprising: providing an initiallysolid pellet of expandable material including a first curing agent andhaving a self supporting characteristic during expansion thereof that isdue to the presence of the first curing agent causing partial curing ofthe expandable material or fast cure time of the expandable material andthe inclusion of the following in the expandable material: i) anacrylonitrile butadiene styrene copolymer: ii) a butadiene-acrylonitrileelastomer and iii) wollastonite; injection molding the expandablematerial into a part having a tubular shape with internal ribs;inserting the part into a cavity that is at least partially defined by astructure of the automotive vehicle; and activating the expandablematerial to cure due to the presence of a second curing agent, so thatthe expandable material expands to a volume that is less than 500%relative to its original unexpanded volume and adheres to walls of thestructure and provides structural reinforcement to the structure.
 18. Amethod as in claim 17 wherein: i. the expandable material issubstantially tack-free to the touch; and ii. the part, upon activation,forms a foam that exhibits a compressive strength greater than about 5Mpa.
 19. A method as in claim 18 wherein: i. the parts are substantiallywithout supports and molded carriers upon insertion into the cavity; andii. the expandable material is at least 95% by eight of the part uponinsertion of the part into the cavity.
 20. The method, of claim 18,wherein the expandable material is not in liquid form prior to partialcuring.